Crystallization of Supersaturated Sodium AcetateA supersaturated solution of sodium acetate is poured onto one small sodium acetate crystal. Crystals form from the liquid immediately upon contact with the seed crystal. A thermometer shows that the crystallization process is exothermic. A chemical hot pack is shown as an example of a commercially available supersaturated solution.

Solutions : FreezePtDepression (20 Variations)It takes 6.86 kg of ethylene glycol (antifreeze) to decrease the freezing point of 6.50 kg of water to -25.0oF (-31.7oC). How much sodium chloride (NaCl) would it take to decrease the freezing point of 6.50 kg of water to -25.0oF? (Assuming all the salt will dissolve in that amount of water.)

A Greener Approach for Measuring Colligative PropertiesSean M. McCarthy and Scott W. Gordon-WylieAs a first step towards the greening of instructional laboratories, we present a new greener version of a laboratory procedure designed to measure colligative properties. The greener procedure substitutes the nontoxic, noncarcinogenic compounds stearic, myristic, lauric, and palmitic acids for the less benign aromatic compounds p-dichlorobenzene, benzil, biphenyl, naphthalene, and nitrotoluene. Achieving educational goals without the concomitant generation of chlorinated and aromatic wastes is shown here to be both possible and practical. McCarthy, Sean M.; Gordon-Wylie, Scott W. J. Chem. Educ.2005, 82, 116.